represent a processing of the input signal to provide an outputsignal variable with or without power amplification

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

10

Figure 1.2

Open-loop control system (without feedback).

•Open Loop and Close Loop Control Systems

Open Loop

control system in which the control action is independent of the output

Close Loop

control system in which the control action is somehow dependent on the output

•Feedback

property of the closed-looped system which permits the output (or someother controlled variable) to be compared with the input to the system(or an input to some other internally situated component or subsystem)so that the appropriate control action may be formed as some functionof the output and input

30/09/2013, Monday

6

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

11

Figure 1.3

Closed-loop feedback control system (with feedback).

•Close Loop

control system in which the control action is somehowdependent on the output

•Feedback

property of the closed-looped system which permits the output(or some other controlled variable)

to be compared with the inputto the system(or an input to some other internally situatedcomponent or subsystem)

so that the appropriate control actionmay be formed as some function of the output and input

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

12

Figure 1.4

Closed-loop feedback system with external disturbances and measurement noise.

(a) Automobile steeri ng control system. (b) The dri ver uses the di fference between the actual and thedesi red di recti on of travel to generate a control led adjustment of the steeri ng wheel. (c) Typi cal direction-

of-

travelresponse.

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

Modern Control Systems, Twelfth Edition

Richard C.Dorf

and Robert H. Bishop

20

Figure 1.10

A manual control system for regulating the level of fluid in a tank by adjusting the output valve. Theoperator views the level of fluid through a port in the side of the tank.